1. Field of the Invention
This invention relates generally to an apparatus for treating flowable material by the irradiation thereof with electrons or other radiation, and more particularly to a device of this type wherein the material is presented to a radiation beam in the form of a substantially uniform, and cohesive thin layer.
2. Summary of Prior Art
Numerous proposals for treating flowable materials with radiation are known, particularly in the area of treating drinking water, sewage, and the like with electrons for the removal of pathogenic microorganisms and other beneficial results. In each of these proposals, the importance of presenting the material to the radiation beam as a thin layer of substantially uniform thickness so as to allow the radiation impinging on such a layer to penetrate therethrough and thereby treat all the material also has been recognized. It has further been recognized that excessive turbulence in the flow of material is to be avoided and that the tendency of flowable materials to form rivulets which increase in thickness the further the material travels over a metal surface should be controlled in order that a substantially uniform level of treatment may be assured for all material presented to the radiation beam. To accomplish this prior proposals have suggested the use of Bernoulli throats as shown in U.S. Pat. No. 3,901,907; open slanted trays as shown in U.S. Pat. No. 3,591,491, or funnels as shown in U.S. Pat. No. 4,074,138; and the use of a trough having a slot in the bottom thereof either with or without a system of counter-rotating rollers for accelerating the flow as shown in U.S. Pat. No. 4,048,504.
Each of these proposals has drawbacks, however. The Bernoulli throat configuration is expensive to build and install and requires added radiation energy to assure penetration through the throat wall and the material; the slanted tray has a limited throughput capability and a somewhat turbulent flow causing nonuniformities in treatment; the rotating drum also has a limited throughput since the radial acceleration of the material must not be so great as to hurl the material off the drum, not to mention sludge build up problems and rather high capital installation and maintenance costs; and the slotted trough also has a tendency toward sludge build up and toward irregularities and discontinuities in flow when counter-rotating rollers are used.